In view of numerous factors such as higher energy prices and environmental concerns, the production of value-added gaseous products from lower-fuel-value carbonaceous feedstocks, such as biomass, coal and petroleum coke, is receiving renewed attention. The catalytic gasification of such materials to produce methane and other value-added gases is disclosed, for example, in U.S. Pat. No. 3,828,474, U.S. Pat. No. 3,998,607, U.S. Pat. No. 4,057,512, U.S. Pat. No. 4,092,125, U.S. Pat. No. 4,094,650, U.S. Pat. No. 4,204,843, U.S. Pat. No. 4,468,231, U.S. Pat. No. 4,500,323, U.S. Pat. No. 4,541,841, U.S. Pat. No. 4,551,155, U.S. Pat. No. 4,558,027, U.S. Pat. No. 4,606,105, U.S. Pat. No. 4,617,027, U.S. Pat. No. 4,609,456, U.S. Pat. No. 5,017,282, U.S. Pat. No. 5,055,181, U.S. Pat. No. 6,187,465, U.S. Pat. No. 6,790,430, U.S. Pat. No. 6,894,183, U.S. Pat. No. 6,955,695, US2003/0167961A1, US2006/0265953A1, US2007/000177A1, US2007/083072A1, US2007/0277437A1 and GB 1599932.
Reaction of lower-fuel-value carbonaceous feedstocks under conditions described in the above references typically yields a crude product gas and a char. The crude product gas typically comprises an amount of entrained carbonaceous fines particles, which are removed from the gas stream. A number of prior known methods are effective for removing carbonaceous fines. Typically these fines are not directly usable, which on the industrial scale, can total to a significant amount of potentially hazardous waste and related disposal costs. Accordingly, the handling, storage and disposal operations of carbonaceous fines waste represent a significant and unproductive expense for the industry.
Thus, there is a need for improved processes and compositions that allow for recovery, recycling, and ultimate conversion of carbonaceous fines, such as entrained carbonaceous fines from the gas effluent after gasification of carbonaceous feedstock, into usable feedstock to generate product gas.